Hurricane FERNANDA (Text)

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Hurricane Fernanda Discussion Number 30
NWS National Hurricane Center Miami FL EP062017
200 AM PDT Wed Jul 19 2017
Fernanda's convective cloud pattern has continued to wither, and
has been accompanied by a general warming of the cloud tops. The eye
is no longer evident in infrared imagery and a 0640Z AMSU overpass
indicated that the eye had become open in the southern semicircle.
Intensity estimates are a consensus T4.5/77 kt from TAFB and SAB,
along with a recent CIRA-AMSU estimate of 82 kt. A blend of these
values supports lowering the advisory intensity to 80 kt.
The initial motion estimate remains 310/08 kt. Fernanda is forecast
to move northwestward today and turn toward the west-northwest by
tonight or Thursday. A continuation of that general motion is
expected through the end of the forecast period due to a strong
subtropical ridge remaining entrenched to the north and northeast of
the Hawaiian Islands. The new NHC forecast track is almost on top
of the previous advisory track, and lies close to the HFIP Corrected
Consensus (HCCA) and TVCN consensus models.
Fernanda is expected to steadily weaken throughout the forecast
period. The first 36-48 hours of weakening will primarily be due to
the cyclone moving over sub-25C SSTs. Following that will be a
sharp increase in southwesterly vertical wind shear to 25-30 kt,
causing Fernanda to degenerate into a post-tropical cyclone by 72
hours. The official intensity forecast follows the downward trend of
the previous advisory and is similar to the ICON and IVCN consensus
models.
FORECAST POSITIONS AND MAX WINDS
INIT 19/0900Z 17.0N 135.0W 80 KT 90 MPH
12H 19/1800Z 17.5N 135.9W 70 KT 80 MPH
24H 20/0600Z 18.1N 137.2W 60 KT 70 MPH
36H 20/1800Z 18.6N 138.8W 50 KT 60 MPH
48H 21/0600Z 19.1N 140.6W 40 KT 45 MPH
72H 22/0600Z 20.1N 143.9W 35 KT 40 MPH...POST-TROPICAL
96H 23/0600Z 21.1N 147.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 24/0600Z 22.0N 152.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
Forecaster Stewart
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